RESUMO
We describe the first implementation of a Josephson Traveling Wave Parametric Amplifier (JTWPA) in an axion dark matter search. The operation of the JTWPA for a period of about two weeks achieved sensitivity to axion-like particle dark matter with axion-photon couplings above 10-13 Ge V-1 over a narrow range of axion masses centered around 19.84 µeV by tuning the resonant frequency of the cavity over the frequency range of 4796.7-4799.5 MHz. The JTWPA was operated in the insert of the axion dark matter experiment as part of an independent receiver chain that was attached to a 0.56-l cavity. The ability of the JTWPA to deliver high gain over a wide (3 GHz) bandwidth has engendered interest from those aiming to perform broadband axion searches, a longstanding goal in this field.
RESUMO
We report the first result of a direct search for a cosmic axion background (CaB)-a relativistic background of axions that is not dark matter-performed with the axion haloscope, the Axion Dark Matter eXperiment (ADMX). Conventional haloscope analyses search for a signal with a narrow bandwidth, as predicted for dark matter, whereas the CaB will be broad. We introduce a novel analysis strategy, which searches for a CaB induced daily modulation in the power measured by the haloscope. Using this, we repurpose data collected to search for dark matter to set a limit on the axion photon coupling of a CaB originating from dark matter cascade decay via a mediator in the 800-995 MHz frequency range. We find that the present sensitivity is limited by fluctuations in the cavity readout as the instrument scans across dark matter masses. Nevertheless, we suggest that these challenges can be surmounted using superconducting qubits as single photon counters, and allow ADMX to operate as a telescope searching for axions emerging from the decay of dark matter. The daily modulation analysis technique we introduce can be deployed for various broadband rf signals, such as other forms of a CaB or even high-frequency gravitational waves.
RESUMO
We report the results from a haloscope search for axion dark matter in the 3.3-4.2 µeV mass range. This search excludes the axion-photon coupling predicted by one of the benchmark models of "invisible" axion dark matter, the Kim-Shifman-Vainshtein-Zakharov model. This sensitivity is achieved using a large-volume cavity, a superconducting magnet, an ultra low noise Josephson parametric amplifier, and sub-Kelvin temperatures. The validity of our detection procedure is ensured by injecting and detecting blind synthetic axion signals.
RESUMO
Microwave reentrant cavities are used for many applications in science and engineering. The potential for both high mechanical tunability and high electric quality factors make them important tools in many areas. They are usually resonant cylindrical cavities with a central post, which makes a small gap spacing with the cavity wall. By adding an arbitrary number of extra posts, they are generalized to a type of multiple post reentrant cavity. This new approach has been theoretically studied but no experimental results have been presented. The main purpose of this work was to compare experimental modes with simulated ones from a reentrant cavity made of forty nine cylindrical posts. Each post could be moved using a screw in order to make tunable gap spacing between the post top and the cavity cover. Eight different gap setups were made making it possible to investigate thirty six different reentrant modes at room temperature. The lowest frequency percentage agreement between experiment and simulation was 91.31%, and the best one was 99.92%. Taking into account all the modes, 94.44% of them agreed above 96%. Thus, we have determined an experimental procedure suitable to investigate the reentrant modes from multiple post cavities. There is a wide range of potential applications for such cavities due to their unique features compared to conventional ones.